Hydraulic turbine



1933- L. F. MOODY 1,929,099

HYDRAULIC TURBINE Original Filed April 13, 1920 4 sheet l INVENTOR .Mlq, 3? M Fa BY fawn,

A ORNEYJ Oct. 3, 1933. L. F. MOODY I 1,929,099

HYDRAULIC TURBINE Original Filed April 13, 1920' 4 Sheets-Sheet 2 INVENTOR 46m; 5. W BY ATTORNEY Oct. 3, 1933. u L F. MOODY 1,929,099

HYDRAULI C TURBINE Original Filed April 13, 1920 4 tset 5 INVENTOR NEYS Oct. 3, 1933. L. F. MOODY 1,929,099

HYDRAULIC TURBINE Original Filed April 13, 1920 4 Sheets-Sheet 4 INVENTOR ATTORNEYS,

Patented Och-'3, 1933 UNITED STATES 1,929,099 HYDRAULIC TURBINE Lewis Ferryv Moody, Philadelphia, Pa., assignor, by mesne assignments, to I. P. Morris & De La Vergne, Incorporated, a corporation of Delaware Original application April 13, 1920, Serial No.

373,545. Divided and this application June 18,

1926, Serial No. 116,813.

Renewed August 8,

27 Claims. (Cl. 253- 118) This invention relates to hydraulic turbines, and particularly to a turbine having a runner of highspecific speed as this term is now generally applied in the art. The chief object of 5 the invention is to provide a turbine in which the water passages and runner cooperate together to attain high specific speed for the runner with highefiiciency for every part of the water stream.

A further object of the invention is to provide a water passage adapted to turn the. water flow from inward direction to outward without the formation of eddies.

A further object of the invention is to combine with this passage a runner of simply formed blading operating in the stream within said passage at high'rel'ative velocity between the blades and the water without causingeddies or high friction losses.

With runners of relatively high rotational speed it is particularly importantto avoid eddies and disturbances of the flow and to maintain smooth conditions of flow without sudden changes of curvature of path or of direction or magnitude of velocity, and it is especially important to simplify and smooth out the flow lines and surfaces at the turbine runner where any irregularities are particularly liable" to be harmful. In order to keepas small as possible the losses in the water passing through a high speed runner it is desirable that, while maintaining the proper action of' the" water on the runner blades, the curvature of the blades and the amount of exposed surface should be reduced. While some attempts in this direction have been made, so far as'Iam aware no definite design has hitherto been evolved' se curing these results or giving the proper relation between the factors controlling the blade shape'and angle. I

The manner of carrying out my invention will appear from the following description and the accompanying drawings, in which;

Fig. 1 is a vertical sectional view of a turbine illustrating one embodimentof the invention. 7

Fig. 2 is a view on enlarged scale of a portion of Fig. 1.

Fig. 3 is a diagram showing the relation of the flow velocities at different points in the water passage.

Figs. 4 and 5 are elevational views illustrating different forms of runners.

Figs. 6 to-9a are diagrammatic views illustrating sections of runner blading, and V Fig. 10' is a plan view of the runner shown'in Fig. 4 at A.

Fig. 11 is a perspective of the runner.

In the embodiment of the invention in Fig. 1 the turbine shown is of the vertical shaft type and its waterways contain a water passage W smoothly. and continuously curving in. the same direction from the radially directed entrance E to the expanding draft tube F without any sudden changes in direction or velocity at any point. For simplicity the entrance is of the radial inflow or Francis type and is provided with inflow guide vanes V which may be fixed or adjustable or both as shown in Fig. 1, and these vanes are set at an inclined position for normal operation so as to give the entering water a whirl. around the axis 20 of the runner. The flow from the head water tothe entrance space E may be-by any convenient intake such as the contracting volute passage22. The outer wall 24 of the passage W curves smoothly from the entrance E into the axial direction at the center and then continues this curvature back toward the-radial direction to merge into the outer wall' 25 0f the conical expanding draft tube The flow is thus guided first inwardly and'then axially and then outwardly in smooth lines of continuously varying curvature, the curvature being at first small, approaching a maximum near the throat or point nearest the axis and then gradually decreasing to the outlet. This continuously' curving wall thus avoids the sudden sharp curvature and subsequent straight line design and sometimes the use of reverse curves which has hitherto been characteristicpractice in turbines having inward flow guide vanes. The preserving of a gradual change of curvature is particularly important with turbines of high specific speed. in which high velocities of flow are direction merging with the runner crown 27 and being resumed by the surfaces of the central cone 28 formed in the inner surfaces of the expanding draft tube F from which the outflow may be collected and passed to the tailwater as by discharge passage 29. The inner wall would be spaced'froin theouter'wall so as to give the proper'area corresponding to the desired velocity at each point of the passage, and due to the. nearness of the inner wall to the axis. its central portion may be of nearly con-'- stant curvature or have points of higher curvature above and-below the throat, but as in the outer wall the curvature will be continuously varying throughout. y V

' Due'tothe whirl "at the entrance caused by 110 the entrance guide vanes the flow lines through this passage W are spirals first contracting and then expanding. Such awater passage maintains smooth conditions of flow and avoids any sudden change in the distribution of velocities and the consequent formation of eddies, and is consistent with minimum overall dimensions of the turbine. The radial inward direction of the flow is well adapted to advantageous methods of regulation as by the adjustable guide vanes 30 in the entrance space. If successive cross sections of the passage W are taken, each section being taken along a-conical surface coaxial with the runner and extending transversely across the flow, that is, substantially at. right angles to the central flow lines, the areas of'these cross sections near the entrance space E will be greater than the cross sectional areas near the runner, that is, these cross sectional areas will progressively decrease from the entrance space E to the runner and beyond'the runner these cross sectional areas then gradually increase from the discharge end of the runner to the final outlet 29, thus in itslower portion providing a draft tubeF radially expanding and simultaneously increasing in cross section so as to efficiently regain both the whirling and meridian components of velocity, a meridian component being that component taken in a plane containing the runner axis. 1

' .This outward flow passage at discharge provides an efficient diffuser in" which the energy of whirl components of flow can be efficiently regained within a limited space; and such a passage enables the overall dimensions of the turbine to be kept a minimum and the whole structure made very compact. A radial outward flow passage is efficient for regaining the velocity head of whirl for the reason that although the radial extent of such a passage may be limited, the actual distance .traversed by the whirling elements of the stream is much greater than the length of the passage measured in the crosssection containing the axis, since the actual paths of the stream elements are gradually expanding spirals. Consequently in such a passage the absolute velocity of flow may be reduced at a sufllciently' gradual rate to provide high efliciency of conversion of velocity head into pressure-head. The turbine of this invention is designed for a comparatively high velocity of whirl during the passage of the water through the runner, and'its reduction in the runner. is moderate in comparison with the-whirl'at entrance to the runner, so that a very considerable amount of whirl still remains at the runner discharge.

This continuously curving vortex form of water passage W thus permits of the efiicient use of high components of whirl throughout and such a whirling stream curving gradually in a meridian plane is especially adapted in the installation of this invention to cooperate with a simple form of runner to attain a high specific speed and smooth and eflicient conditions of flow.

It being'understood that the entrance guide vanes or wicket gates are set at an inclined position for normal operation, so as to give the entering water a velocity of whirl Cuo at a radius To, let uscall the whirl in the water after leaving the runner Cu3 at aradius r3. This discharge whirl may be considered for simplicity at a position ;1'3 equal to 1'0 .(see Fig. 2). All entering streams pass the outflow or inner .edges of the guide vanes at radial position r0, Iandall pass in which:

H=efiective head on turbine e=hydraulic efiiciency of turbine N=rev. per-minute of turbine and g acceleration of gravity.

If e be made substantially the same for all parts of the turbine, the second member of this equation is a constant for all stream elements, and if r: is chosen the same as m, we see that cuocua'is the same for all stream elements. If

.guide vanes of uniform section are used, 0110 will be constant and hence Cull is constant. It may also be seen that TOCUO represents the torque exerted by the entering water (per unit of mass) and T3Cu3 that of the leaving water, the difference being the torquev exerted on the runner. Under the above conditions this is evidently constant for all stream elements and hence the Water passing through the portion of the runner nearest the hub must exert upon it just as much torque as that passing through the outermost portion. Since the radius of the portion near the hub is much smaller than that of the outermost portion, there must be a compensatingincrease in the force exerted by the innermost'stream elements to give the desired constant torque.

.In the combination of this invention'this increase in force can be obtained by a greater defiection of the water passing through the runner; that is, the runner vanes near the hub'may be formed to turn the water through a much greater angle than the outermost portions of the vanes. Indeed, in the turbine of this invention if the difierence in radius is too great, the innermost vane section if designed for constant torque will result in a hooked form of extremely curved shape '(see Fig. 8 and the vane formation C in Fig. 4), the entrance edge being inclined backward so as to point in the direction opposite to the runners rotation, in order toproduce sufficient deflection in the water to give the necessary driving force and torque to the vane. Such a hookedform of vane section results in a complicatedsurface formation and with such a hooked form of vane there is danger of the lines of flow departing from the vane surface and causing eddiesand losses. I r

In accordance with the relations above established, the flow'bothas to magnitude and direction may be determined at the entrance to and discharge from the runner whatever its position in the'passage or thecurvature of its edges as viewed in projection, as in Fig. 5. The runner may be placed in any one of various positions, such as A, B, C or D, and the vane angles determined, the blades being inclined at their'entrance and discharge edges at an angle coinciding with the relative motion of the water at each point'along said edges. For any of these positions A, B, C or D the vane edges may have anyone ofa wide variety .of shapes. In so-called Francis type turbines it has been usual to give theprojected vane edges and'the transverse elements of the vanesurfacea pronounced curvature with the object of keeping these edges and elements as nearly normal to the flow lines as possible at all points. Departing from this pracmaoyeaa V "the bla'de area and the consequent? friction losses as much aspossible andthe vaneedgesas viewed 1 in projector) are substantiallystraight extending di'rectly across the passage. If sections are taken transverseto the meridian sections it is seen from' .Figs. 3, 4, 6 and 6a that the upper'bIadesurTace is convex andthe lower surface con'cave; along transverse elements.

In the runner of this in'venjtio n. therefore; the elements of the vane surfaces and the-entrance and discharge edges cut across theflow on the shortest possible lines and produce a simple form :of-surface avoiding sharp and complicated curvature and "resultant eddy losses and maintaining efllcient contaictwith the-stream at all points. The bladeswill in most instances vary from a relatively fiat-shape at "the tip to a relatively curvedformat the hub 'andfthe relative shapes of-the blades'urfaces will change according to the I position of the blade in' the curved water *passage W, that1is,'according asthe blade. isof the involving, however, a variationinthe contour of the runner blade surfaces." Such'variation willin .certain positions of. the :runner tend toward rela tive simplicity in form of the runner surfaces =and=especially in 'the1diagonal inwardflow runner such as A,a' (Figs. i4 andl0) or B, b (Fig. 5) will give a. particularlyadvantageous combination, makingthis type of the 'runner'in many re- :spects'preferablej a s To compare the characteristics oI'the turbine for difierent positions of the runner, four typical forms are'illustrated in the FigsA and '5where'i1'1 the blading A is of the inward diagonal flow type, B chiefly of axial and slightly radial flow type, 'C of. strictly axial flow type'and-D of diagonal out- .wardflow type; each runner having four blades. In Figs. 6, 6a, 7, 7a, 8, 8a, -9 and 9a conical or cylindrical sections 1 of these typical vanes are shown on lines 6-6, '6a-'-6a, 'l7, 7a+7a, etc. with, velocity triangles, illustrating j the relation of the surface contours to the fiow at the different points in the passage W. Inthesetriangles:

c1 denotes the absolute velocity of the water at *entranceinto-the runner. c2 denotes the absolute velocity of the water at exitfrom the runner.

wi denotes the relative velocity o f the 'water'at (entrance into the 1 runner.

.wz denotes. the relative velocity of the water at exitfmm'the runner. i

, Cul denotes the absolute velocity of whirl" of the "waiteratentrance. f r cuz denotes the absolute velocityoi whirl'of the water atexit.

112 denotes the .55

velocity of then inner at'exit.

; If-dottedlinest, u and t, w (FigsA and 5) are the help-of the diagram, Fig. 3. shows graphically the variation of cm and our taken to represent the courses 'o'i elementary stream particles through the turbine, as shdwn -'by circular projectioninto the meridian plane (the actual courses being 'spiralscontained in surfaces of revolution of which t, u and t, u are the generatrices). let us consider the forms "of vane sections at'hub and t'ip -req uired for-each alternative position of the runner. Calling, as

the absolute whirl at 1-1, the entranceedge of the vane, and cu'a the fwhirl at T2, the discharge edge .of .the vane, we shall have as 7 already explained ToCuo TlCul and racus rzctzy so that 1L1Cu1-u2Cu2 gH6. 1

Hencejwhenever a stream element enters and leavesthe runner at the sameradial distance before Cuo the absolute whirl of the water at point'ro at discharge from the guide vanes; cus the whirl at point 3; and similarly calling cur.

from'the axis, as in axial flowrunner C; so that u1=uz, we shall have cuigreater than cm and consequently wuz greater than war, since wu2= i "gH e He 142' u1 (See Figs. 8 and 8d) Figs. 8 and 8a are developed cylindrical sections of the vane, on the lines 8.8 and 8a-8a of Fig. 4.; y f

Assuming that inpassing through the small space measured in the 'meridian fdirectio'n. repreponent of flow will remain substantially constant, or Cm1:Cm2, approximately. we shall have ,fl1 flz, so-that the center line of the vane sectionshould be concave when viewed from'the jfa'ce or'driving 'senting the depth of the vane, the meridian com- I side and'convex whenuviewed from the back.

"Hence,,the characteristic shape of an axial-flow runner, when properly designed to suit the relative directions of the, entering and leaving water, is a concave form when viewed from the face side. of the vane. This aplies to every vane section where the meridian projection of the flow ispure1yaxia1.-*

In a runner of the outward diagonal fiowtype,

Fig. 4, D, considering the flow on conical sec-' Inan inward-flow runner such as A, developed conical sections 6 6 and fia-Ga of whichare shown in Figs. Band 6a, if it; exceeds ilz'by a sufficient amount Cul, Willbe, nearly equal .to or even less than cur-and consequently wurwill be.

greater than we. Hence 62 will be exceed B1 and the vane will be convex when viewed from the face or driving side. r r

The relations between the velocities at entrance and discharge canbe more easily visualized with This diagram for diilerentv'alues ofrvby'means of two rectangular hyperbolas drawn through the 'points 10cm and mods; and also shows .by means of a wul and wuawhich are given directly by the inas e tercepts between the line. of u and; the corresponding h'yperbola;

As the type of runner ischanged fromA to C,

passing-through various intermediate positions 'such as B (Figs. and 6 and 6a), rrand 1 2 will gradually approach each other and become equal for runner 'C.. Runner A, as just shown, .has

vanes convex toward theface, while runner C has 3 V vanes convex toward'the back. At some intermeii 1o diate position, such as B, the vane will become fiat (Figs. 5;? and 7a) and on eitherside of this position the vane willcurve in opposite directions. This flat form .of vane willcorrespond to just enough excess of 11 over r'i to give a value of win sufliciently greater than will so that p1 will exceed 132 bythe amountv; 6 being the angle subtended "by the vane. (SeeFigs. 7 and 7a) If the values I of T1 and'rz-correspond to the points of intersection of, the hyperbolas with the line of u; win

and wuz will both be zero, and 81 andfiz both equal v to 90; that is,'the vane will 'be straight andparallel to the axis;v This conditionwill give mini- 7 mum relative velocity between the vane and the water, the'vanevelocity being equal to the absolute whirl at both entranceand'discharge, but

In order to produce a runner having vanes of simple form and of smooth "curvature at all oints,itisdesirable'to avoid any surfaces ccncave atone place and'convex atanothensince' such reversals of curvature "introduce un'necesa sary complications inthe form, are difficult to design and construct, and increase the liability of the actual "lines 'of' fiowdisagreeing withthe vane form; with the consequent formation iof ed dies and loss'in'eificiency. Such reversal" of vanes direct the flow with radially inward and curvature is found in runners as heretofore constructed. 1 In such runnershaving complicated surfaces with sudden changes in curvatureacross the flow lines, any variation of the actual flow lines from those assumed particularly likely to occur when operating under other thannormal conditions ofgate' and the speedjwill result in serious disagreement between the actual vane shape and that required by the flow,

In this invention such values may be selected for 7'1 and r: at every section (n being greater than n at every section although 11 'and'rz may be nearly equal at the outermost section) that the vanelis'either almost completely flat throughout, or slightly convex toward the face at all points. (See runners A and .B; Figs;'4, 5, 6,6(1 and 7, 711)". Forusualconditions'a slightly convexv face at all sections may he preferred approaching the runner A form, for instance, since by employing such a form it is possibleto provide a considerable width of blade where the blade joins, the hub nati'onat this section', and thus to provideample strengthufor I the blade, particularly for resisting tangential blows when the 'vane strikes trash 'or V obstacles carried by the water; Every section of the vane taken along the surface of a cone cutting through the vane in the general direction of flow and having its axis coinciding with the axis of the runner, such'i'or example as the cone generatedby revolving theline 7-7 of Fig. 5 about the runner axis willthen be a spiral ora curve'slightly .concave with respect to a point lying in the turblneiaxis and the entrance edges of the blades will be;inclinedat an angle coinciding with the relative-motion of the waterat each pointalong the edge. It should be understood that in the description of the blade shape,the shape referred to, unless otherwise specifically pointed out, is

that of the central surface midway between the front and back surfaces, which may, of course,

be slightly different fromrthe central surface due to the thickness of the metal .and the taper toward the edges.

Such a diagonal inward flow runner also'per- .mits the'blade surfaces to be formed by nearly straight line elements in a very simple manner;

and thissimplicity is consistent with the maintenance of constant torque at all points across the flow; and consequently with the, attainment of high efiiciency. 7

The, relatively large hub of such a diagonal runner is also' particularly desirable, as in the turbine ofthis invention thev tendency of the runner blading is to become less simple in contour in sections approaching the axis since the whirl velocity of the stream lines entering the runner varies inversely with the radial distance ottheelement-from the axis, as shown in Fig.

3. In Fig. '4, forinstance, the-blade of theaxial runner Cat its-inner portion develops toward an undesirable backward curvature, making it difficult to adhere-to the useof straight line elements Without departing from the shape required by the entrance and dischargevelocities. With the enlarged conical hub H, naturally'usable in the diagonalilow portionsof the'passage W, the runner blades donot approach. closely to the axis and complicated reverse curvatures are thus avoided. "The variation of curvature for different portions of the runner is therefore kept within. moderate limits andthe' form of the vanesection is made favorable to high efliciency at all points. 1 a ..1

In this type" of turbine the entrance guide tangential velocity components around the turbine axis into a transition space in advance of the runner and the flow in this transition space is turned partly toward thev axial beforeenteringwthe runner: The runner at the inner or hub ends of "the blades is above the level of the plane of the lower ends of theguide vanes, while the outer ends of the blades are below said plane, and the entrance edges of the blades make acute angles with saidv plane containing the lower ends of'said guide vanes.- The entrance edges of the runner blades are thus positioned only a short distance-from the discharge edges of the guide vanes 30, justsufficient to permit a smooth gatheringand slight turning of the flow. The turning or transition of the flow begun in the transition spaceis-alsosmoothly continued in the flow through the runner and preferably-the runner blades are formed-and spaced so that when viewed in a plane perpendicular to the axis there will be open spaces at the 'outer portions between the discharge edge of one blade and the entrance edge of the next succeeding blade.- In the specific embodiment of the invention herein these open spaces extend inward; from the runner-periphery, throughout at least the major portion of the blade length. orlin some cases completely to the hub so that where the open spaces occur over the major extent ofthe blades, if a line is of. will intersect the .nextadjacent. vane, this overlappingproviding'definlte channels of g'uid-g anc mane inner. flow lines with. their relatively high degree of whirl and. permitting the bladesto be strong. at their innerg'portions and strongly connected to the hub so that a shroud 4 ring at the outer ends may be'dispensed with. Furthermore, since. the. fiow through this preferred diagonal runner A, a MB, 1) is in a diagonal inward direction between radial and'a'xial, the

points. of entrance of the various elementary streams are farther from' the axisthan the correspohding' points of. discharge. As. a result, the points ofent'r'ance of the vanes have a. greater velocity u; than the points of discharge, flz, .a con-.

dition favorableto low relative velocities of. the vanes. with respect to the water atboth points, since as explained abovefthewater possesses a somewhat greater velocityfofiwhirl before' en- .trance' intofthe runner than it does after discharge from the runner.

The diagonal position 'of the runner blading,

while leaving. atr'ansition. spaceYT at least as wide as "the runner blades viewed in meridian plane and suflicient for the whirling flow to collect into'a continuous. mass and turn from the radial inflow, guide vanes V, reduces the length of this ,transitiofispaceand so reduces the velocity of flow at. an earlier'point, in the water passage, thus reducing, thewall. area in contactwith the highvelocity portion of the stream. ItIshould be ,borne in mind that'the turbine of this invention'isparticularly.adaptedto' the productiono'fhigh specific speeds. To thisend the water. passages and runner mutually contribute and combine together" to maintain; the eflieiencyand smooth flow, In the. design, of] the meridian section of thewatenpassage in which the runner operates it. is of importance to' avoid curves of. small radius and rapid changes, in

curvature, the variation ofthe curvature of both wallseo-f the passage W being gradual andcontinuo'usthroughout. The use at walls of;gr adu-- ally varying. curvature in the. meridian section is of importance in the turbine'of high specific speed forthe reason that notonly are high velocities of whirl employed but high meridian components of, velocity are also used.-

of the whirl previously referred to, which takes place around the turbine axis, that is, in planes perpendicular 'to the axis; The, whirl" the meridian plane may be "called a secondary whirl. Y

,highest near the outer wall and-lowest near. the, axis. These meridian components of velocity are denoted ongthe 'diagrarnsby the symbols cm1 and cm; in 1112 .6, 6a, 7, lafetc and it will benoted -that at each section the-values of. cm1i andc'mzat the section near. thehub are smaller than those at the' sectionhear the tips of. the

blades. This'variation'is due'to the centrifugal forcelof the secondary. whirl which increasesthe pressures near the turbine axis and correspond-J h g ly decreases the meridian velocity components.

The. turningof the stream in the meridian plane involves, awhirling of the water particles in this plane, which is perpendicular to the plane.

In the design of the runner or this invention, due account is takenof variation of meridian velocities; and all harmfulv effect of thesecondary whirl is avoided. If, however, there were sudden variations in curvature of the meridian I section'of the passage, there would be sudden-un avoidable changes in the centrifugal:pressures and in the distribution of meridian velocities,

conditions which lead to the refusal of the waieizto followthe contour of the walls, and-to the] formation of eddies and wasteful disturbances, Summarizing the operation of the turbine of this invention" used for instance with the pre ferred radial type of inward flow guide vanes and diagonali 'inwar d flow runner, the water enters in'en'trance space. Ebetween guide vanestV in streams progressing inward with a tangential whirl. ,The walls ofthe water passage W begin a gradual turning of this whirling flow toward 1 the axial direction and provide afree transition space .T between the entrance and the runner wherein the flow lines'without obstruction collect into a single whirling mass. The gradual turn ing in a meridian plane'of this rapidly whirling flow is continuedthroughout the water .passage WI on lines of slowly changing curvature. Due to the' high speed of rotation the combination of this invention involves comparatively light torque on the. runner blades so that the whirling'fiow passes'downthrough the runner. which rotates] rapidly. with respe'ctfto the stream which is itself rotating The runner blades glide through the stream with little disturbance and. cause only amoderate change in velocity of the flow, which a'sjitleaves', the runner still is whirling withcon- 1 siderable velocity; Beyondthe'runn'er the water passage W continues thesame, smoothv linesof gradually changing curvature andthis curvature at the runner is continuous" with that at the entrance end of the draft tube F; the curvature then gradually decreasing toward the discharge end of the tube. The whirling outfiowfrom the" ruhner'thereforeis consolidated in the free transition space below the runner again forming asmoothly whirlingmass which is then gradually from tip to hub, the terrr homogeneous meaning that thecenter of curvature continuesjon the same side of the blade and, the curvature does-not-v 'It should not be inferred that the water passage wouldfbe of exactly the same design regardless oi'the position, of the runn'er. It would be of, the same general form, but as soon as thepreferre'd' position of the runner isselected, the pas sage would, be designed to start the gradual de-' cele'ration of velocity at the runner discharge, the cross-sectional areas and the-resulting spacing of the outer and inner wall being proportioned accordingly.

The above description includes a general meth 0d at desisnen c l le pn or th t r in of this iriventiom and this method as (illustrated re n ay, be a pl d t e urbine nwhi ih the 2 de'celeratedas itpasses to the outlet, the particles self be eliminated. Moreover, the avoidance of itself 1 the present invention:

5' tofore been developed-largely bythe experimental or cut-and-try method, and the absence of an adequate general theory has not permittedsuch runners to be intelligently altered 'to any material extent without introducing uncertainties as to the performance, to be expected. For example, there has not heretofore been disclosed any general method ordesign of such axial flow run-- ners of highspecific speed by which the design by which the type maybe changed from purely axial to agreater-orlesser degree of inward or outward flow.

In the turbine of this invention theseuncertainties are overcome in avoiding the complicated shape of runner blading which has been used in 'highspecific speed turbinesof the prior art, and in eliminating the sources of imcertainty in regard to' the'fiuid friction losses "in the'runner. In particular some of the causes of uncertainty which are avoided in this invention are the"spoon shaped c'urvatureof the runner ,vanes which has'heretofore been common, thatiis', the pronounced curvature'i of the meridian sections'of' extending in thejgeneral direction of flow; the

use of a runner band or shroud ring introducing a surface having highrelativevelooity with re-' spect'to the: water; ,andiin addition the employ-l ment of sudden changes of curvature in the water] passage hasbeen abandoned. f d

In the runner of this invention all' of'the'vane sections can be'made with only slight, curvature in the direction of flow so that the passages be? tween the vanes will be substantially straight.

By this meansthe uncertainties due to" lack of,

knowledge of losses in elbows can beavoided and the lossdueto curvature in the passage can itthe necessity for deflecting the waterjthrough large angles, permits the lengths'of thevanes to be reduced and their "spacing increased, thus reg ducing the areaof the exposedsurface as illustrated in the four bladed runners'of Figs. 4' to 10.

The passages between the runner vanes are, therefore, in the turbine of this invention :re-

duced to short sections of straight conduits for blades'ofgthe runners of Figs; 4 to 10 are so formed and spaced that open spaces are left be-,

tween at least the outer portions of the blades the blades are nearer'together and overlap, that is, a line at right angles to the lines of flowland extending frorn the edge'of one ,blade will inter-- sect'theadjacentblade. .7

T his application, directedrgenerally to theopen components with respect touth'e, turbineaxia a W runner having blades with outer endsrbelow'said vanes andinner ends extending above the lower space extending between said vanes and said runmay be-a'itered to give lower or higher speed, or

which the fluid losses canbe calculated. The

as seen in a plan view.- At their inner portions.

1 type of propeller runner, is a division of the co-' ners are all old in theart, and it is not intended to claim anyone of these 'types' as representing in endsof said vanes,said blades being formed and spaced to'leave throughout at least-the major v portion of their length open spaces between them' Runners of high specific speed having here-- when, projected on a plane perpendicular to the runner' axis and the blades also being arranged so that'throughout said majorportion a ,line;ex-j' tending from the edge of one blade, perpendicular to the flow through the runner, will falloutside of the adjacent blade, and a vane-free transition mi blades and bounded on the side toward th axis byia surface of revolution.

2. In a hydraulic turbinefof high specific speed the combination 'of guide vanes directing the flow with radial inward and tangential velocity components with respect to the turbine axis, a runner having, unshrouded blades with outer ends below said vanes and inner ends extending above the lower ends of said vanes, said blades being formed and spaced to leave throughout at least the major portion of their length open spaces between them when projected on a plane perpendicular to the axis and'the blades also being'arranged so that throughout said major portion a line extending from the edge of one blade, perpendicular to the flow through the runner, will fall outside of the adjacent blade, and providing a vane-free transitionspace between said guide vanes and said runnefblade s. r

3. In a hydraulic turbine of high specific speed the combination of guide vanes directing the flowwithradial inward and tangential velocity components with respe'ct to the turbine axis, a runnerhaving less than six blades: with outer ends below said vanes and inner ends extending abovethelower ends of saidvaneasaid blades being-formed and spaced to leave throughout at leastthe major'portion of their length open spaces between them when projected on a plane perpendicular to the axis and'the blades also portion a line extending from the edge of one blade, perpendicular to the fiow'through the runner, will fall outside of the adjacent blade, and a vane-free transition spaceiboundedby inner V and outer surfaces of revolution, the inner surface turning from radial direction toward axial direction to conform'in'contour to the runnerhub.

In a hydraulic turbine of high 'speciflcspeed' thecombination of guide vanes directing the flow withradial inward and tangential velocity components with respectlto the turbine axis, a run-- ner havingless than six unshrouded blades with outer ends below said vanes and inner ends extending above the lower ends of said blades, said blades being iormed and spaced to leave throughout at least the major portion, of their length openspaoes therebetween when projected on a plane perpendicular to the axis and the blades also being arranged so that throughout said major portion-a line extendingfromthe edge of one blade, perpendicular to the flow through the runner, will fall outside of the adjacent bladeyand wastes? a vane-free transition space between said guide vanes arid'said runner blades. i 6; In a hydraulic turbine of highspecific speed the combination of, guide vanes directing the flow. with radial inward and tangential-velocity, components'with respect to the turbine axis, alrunner having unshrouded blades withouter ends below said vanes and inner ends extending above the lower endsof said blades, said blades being formed and spaced to leave throughout; at least the major portion of their length open spaces therebetween when projected on a plane perpendicular to the axis and the blades also beingarranged sothat throughout said major'portiona line extending from the edge of one :blade, perpendicular to'the' flow through the runner, will fall outside of the adjacent blade, a vane-iree transition space between'said guide vanes and runner blades, and a draft tube having a relatively long symmetrical portion in comparison with the runner diameterwith gradual and-com tinuous enlargement oi area so asefiiciently'to convert velocity head into pressure heads,

"'7. In a hydraulic turbine of high specific speed the combination of guide vanes directing "the fiowwith radial inward andflt-angential velpcitycemponents with respect? to the turbine axis, a runner having unshrouded blades with outer, ends below said vanes and; inner ends extending above the lower ends of said blades, said blades being formed and spaced to leave throughout at least the major, portion of their length openspaces therebetweenwhenprojected on a.

nqieular'to the axis and the blades Ialsobeing arrangecl so that throughout; said major' portion a line extending --from I the edge oli one blade, perpendicular to the ,flow through therunner, will fall oiitside of; the adjacent blade,

and a vane-free transition space between said guide vanes and said runnerblades bounded by inner and outer surfaces of revolution, theinner surface turning irom rad al toward axial direction to conform in. contour to the runner 8. In a hydraulic turbine of high specific speed; the combination of guide vanesf directing flow, with radial inward and tangential velocity components with respect. to-the turbine axis, a runnerhaving less than six blades with outer ends below said vanes and inner ends exf tending above; the lower ends of said vanes, said being arranged so .that throughout s aid major portion a line extending from the edge of one blade, perpendicular to the flow through the runner, willrfall outside of the adjacent blade, and, providing a vane-free transition space between said} guide vanesand saidrunner :blades boundedby inner and outer surfaces of, revolu tion, the inner surface turning from radial toward axial. direction to 'coniorrninieontour to the runner-hub.

' taaxial andig'uidefvanes directing the flow with radial" inward and tangential velocity, componerits with'respect to the turbine axis, a runner having a hub tapering from a large diameter at itsentra'nce portion to 'a-small'di'ameter at its discharge portion, and unshrouded blades .ex--

diagonally with respect to the axisand heineiormedand na ed o 1 a ath ushoutat portion a line; extending from the edge-of one blade, perpendicular to the flow through the runner, will fall outside of the adjacent'blade, the inflow edges of said blades intersecting the hub at a point which is radially disposed: from the runner axis by a" distance slightly greater than one-half the greatest tip radius of the blades. 7

10. In a high specific speed hydraulic turbine the combination with an intake adapted to direct the now, radially inwardly and impart a whirl to it, of an outlet through which the flow passes outwardly away from the axis and with a whirl, a conduit continuously curving in p the same direction-and leading from said intake'to to leave, throughout at least the major portion of their'length, open spaces therebetween when projected on a plane perpendicular to the axis and the blades also being arrangedSOothat throughout said major portion a line extending from the edge of one blade, perpendicular to'the flow through the runner, will fall'outside of the adjacent blade;

11. In a high specific speed hydraulic turbine the combination with an intake adapted toqdirect the waterjradially inwardly and impart a whirl to-the fiow, of adjustable guide vanes, for

varying said whirl, an outlet through which the,

flow 'p'asses. outwardly and with a whirl, a

conduitcontinuously curving in the same directhroughout at least'the major portion of their, length, open spaces therebetween when projected, on a plane perpendicular to the axis, and the blades also being arranged sothat throughout said major portion a line extending fromthe edge of one blade, perpendicular to "the :flow through the runner, will fall outside of the adjacent blade. 7 l

12 In ahigh specific speed hydraulic turbine structure the combination with aniintake passage and a discharge passage relatively'closely spaced to bring'said passagesintoproximity with each other, of a conduit bounded bysurfaces of revo1u tion continuously curving in one; directionand leading from said intake to said discharge, anda,

turbine runner in said conduit having blades;

formed andspaced to leave throughout at least the major portion of their length, open spacestherebetween when projected on a plane perpen dicular to the axis and theblades also being arand having blades formed and spaced to leave,

ranged so that throughout said major portion, a

line extendingfrom the edge of one blade, perpendicular tothe flow throughthe runner, will ialloutside of the adjacent blade. 9. Ina hydraulic turbine of high specific speed the combination of a conduit turning from radial 13. In a high specific ,speed hydraul icturbine the combination with an entrance space having aninwardly directed flow, of means for imparte i said flow, having blades iormedand spaced to leave throughout at least the major portion of their n h ns eces t e e e n wh p te e aneine i l r to he en ma;

the blades also being arranged so thatthroughout said major portion a line extending from the cent blade.

edge of one blade, perpendicular to r the flow through the runner, will fall outside of the adjacent blade, and a continuously curving water passagereceiving the flow from said runner and turning-it gradually toward the radial outward direction in diverging spiral flow lines.

14. In a high specific speed hydraulic turbine the combination with an entrance space having an inwardly directed flow, of means for impart-' ing a whirl to said flow, a spreading draft tube adapted to decelerate the whirling outflow on expanding spiral lines, a water conduit of continuous curvature guiding the flow from. said entrance space to said draft tube, and a runner in said passage having blades formed and spaced to leave, throughout at least the major portion of their length, open spaces'therebetween when, pro-- 7 jected on a plane perpendicular to the axis and the blades also being arranged so that throughout said major portion a line extending from the edge of one blade, perpendicular to the flow through the-runner, will fall outside of the adja- 15. In a high specific speed turbine the cornblriation with a curvingwater conduit, of means for directing the fiowinto said passage with a whirl, and a runner in said passage spaced from saldmeans and comprising vanes having substantially straight line elements extending across said passage and formed to -receive a uniform torquefrom the'whirling flow=at different points across said passage, said vanes havingfblades .j formed and spaced toleave, throughout at least the major portion of their length,,open spaces therebetween when projected on a planeperpenf dicular to the axis and the blades also being whereinthe transition space is bounded on the arranged so that throughout said major portion a line extending'from the edge of one blade, perpendi'cularto the flow through the runner, willfall outsideof the adjacent blade. 1 16; A runner for a high specific speed hydraulic turbine having diagonal blades with homogeneously curved driving surfaces convex away-from the runner axis and'back surfaces concave to the runner'a'xis, said blades being formed and spaced to leave, throughout at least the major portion of their length, open spaces therebetween when projected'on a plane perpendicularto the'axis and the blades also being arranged-so thatthroughout said'major portion aline extendingfro'm-the edge of one blade, perpendicular to the flow through the runner, willfall outside of. the adjacent blade.

"--:'17. The combination as set forthiin' claim 9 wherein-.said'conduit has its inner surface formed as a curvedsurface' of revolution top'provide a transition space and said surface being substantially continuous with the contourof the runner hub, so as to turn the water gradually andsmoothly; ,7 V V 18-, The combinationas set forth in claim 2 said blades having its upper surface concave along the radial elements thereof and convex in a directidfi transverse thereto, said blades in plan view being non-overlapping throughout at least a major portion of their length andthe'blades also continuous in contour'n being, arranged so that throughout said major portion a line extending from the edge of one blade, perpendicular to the flow through the runner, will fall outside of the adjacent blade.

' from theedge of one blade, perpendicular to the flow through the runner, will fall outside of the adjacent blade. I V

21. A high specific speed hydraulic turbine propeller runner comprising a hub having blades extending outwardly therefrom, each of said blades having at least a portion thereof concave along its outwardly extending element and being convex over at least a portion of its surface when taken along a transverse element, said blades in plan view being non-overlapping throughout at least a major portion of their length and the blades also being arranged so that throughout said major portion a line extending'from the edge of one blade, perpendicular to the flow through the runner, will fall outside of the adjacent blade.

22. The combination'in a high'specific speed hydraulic turbine, comprising a conduit turning from radial to axial, guide vanes for whirling the inflow through said radial portion, a runner spaced from said vanes to form a transition space which is bounded on its inner surface by the conduitwall formed as a curved surface of revolution continuous'with the runnerhub, said runner having blades which in meridian section are concave on top and in sections transverse thereto are convex on top,'said blades in plan view having open spaces between them throughout atleast a major portion of their length and the blades also beingarranged so that throughout said major portion, a line extending from the edge of one blade, perpendicular to the flow through the runner, will fall outside of the adjacent blade.

'23, The combination in a high specific speed hydraulic turbine comprising a runner having a hub carrying blades which are relatively flat in the direction of flow thereover, and which in plan view have their adjacent edges'spaced so as to leavegthroughout at least the major portion of their length, open spaces of materialwidth and the blades also-being arranged so that throughout said major portion a line extending'from the edge of one blade, perpendicular to the flow through the runner, will fall outside of the adjacent blade;

means} forming a passage including a vane-free transmission space for conducting'flow to "said runner, guide vanes adapted to impart whirl to' the'infiow, and an annular draft tube having a central 'core terminating at its upperend substantially adjacent said hub, said core having a smaller diameter at anintermediate point of its length than at a point adjacent to the runner hub.

hydraulic turbine comprising a passage turning 2 The combination in a high specific speed from 'a radial to' an axial direction, guide vanes;

adapted to impart whirl tothe inflowing fluid,

sage in spaced relation to said vanes to form a transition spaceof substantially constant volume throughout turbine operatiomsaidrunner having a relatively small number ofdiagonal blades, the

. and an unshrouded' runner disposed in said pas-- adjacent edges of successive blades being disposed, throughout at least the major portion of the length of said blades, a substantial distance from a common meridian plane so as to form in plan view open spaces between said adjacent edges.

25. The combination in a high specific speed hydraulic turbine comprising a passage turning from a radial to an axial direction, guide vanes for whirling the inflowing fluid, and an unshrouded runner disposed in said passage in spaced relation to said vanes to form a transition space of constant volume throughout turbine operation, said runner having a relatively small number of diagonal blades which are relatively flat in the direction of flow thereover and which throughout at least the major portion of the adjacent edges of successive blades are disposed a substantial distance from a common meridian plane so as to form in plan view open spaces between said adjacent edges, and the blades also being arranged so that throughout said major portion a line extending from the edge of one blade,perpendicular to the flow through the runner, will fall outside of the adjacent blade.

26. The combination in a high specific speed hydraulic turbine comprising a passage turning from a radial to an axial direction, guide vanes for whirling the inflowing fluid, and an unshrouded runner disposed in said passage in spaced relation to said vanes to form a transition space of constant volume throughout turbine operation, said runner having a relatively small number of diagonal blades which throughout at least the major portion of the adjacent edges of successive blades are disposed a substantial distance from a common meridian plane so as to form in plan view open spaces between said adjacent edges and the blades also being arranged so that throughout said major portion a line extending from the edge of one blade, perpendicular to the flow through the runner, will fall outside of the adjacent blade, said blades also being relatively flat in the direction of flow thereover, and being disposed at least adjacent the blade tips, in a more nearly horizontal than vertical position.

2'7. The combination in a high specific speed propeller type hydraulic turbine comprising, a

passage turning from a radial to an axial direction through a transition space, guide vanes for whirling the inflowing fluid, and an unshrouded runner disposed in said passage in spaced relation to said vanes to form said transition space, said runner having a relatively small number of diagonal blades which throughout at least the major portion of the adjacent edges of adjacent blades are disposed a substantial distance from a common meridian plane so as to form in plan view open spaces between said adjacent edges and the blades also being arranged so that throughout said major portion a line extending from the edge of one blade, perpendicular to the flow through the runner, will fall outside of the adjacent blade, and said blades also being inclined so as to form at their inner portion an overlapping relation between the same when measured in a direction normal to the flow through said inner portion.

LEWIS FERRY MOODY. 

